The type inference scenario that didn't work, was supposed to be
implemented, and was ultimately added for 2.058 is,
Given this function:
bool contains(int[] arr, scope bool delegate(int) dg);
You should be able to call it like this:
contains(arr, x => x == 2);
// Alternatively,
contains(arr, (x) { return x == 2; });
This was not previously possible, you had to make the parameter
types of those delegates explicit.
There is a bug that sometimes makes this inference crash even
with 2.058 though, but I think it might have been fixed for the
next release already (I got the same error message as one I saw
in a bug report for a recently fixed bug).
Now, it would be nice to have the inference you ask for as well,
but I don't believe it's what was talked about.
Of course, you might be referring to conversations I missed...